Hey there, this is a horrifically late response but there isn't that great of a difference to be honest and as long as your uni grades hold up then you won't be at a great disadvantage (if any). I'd look into doing first year physics at uni as breadth and getting some practical experience (eg volunteer/work at a vet clinic) to max your chances.
Just a word of warning for anyone thinking of DVM at unimelb - the UniMelb veterinary department got some significant cuts this year which includes shutting down the U-Vet animal hospital in Werribee some time in the future. I dropped out of the course before this was announced but from what I hear from my friends who are still there, there is a lot of concerns among students over how this will affect the teaching there. If going interstate is an option, I'd recommend looking into the Bachelor of Veterinary Biology at USYD instead.
